Let's say I am working on a particular function. It would be really nice to be able to hit a hotkey and all other code, except the function and function's doc-head, fades out --providing me only what I am working on. This reduces clutter in my workspace and keeps my focus on only exactly what I am working on.

You can fold the whole buffer by level using ["ctrl-k", "ctrl-1"] (which will fold everything up to the first level - that's as minimalistic as it can get) but you would have to unfold the code until you can see your function.

You can also select the code above your function (and below) and then press ["ctrl+shift+["] which will fold the current selection. Then you can ["ctrl-k", "ctrl-0"] to unfold everything. Do a find for "fold" on the default keybindings.